Theoretically, the best place to put the TC is in the ball itself by drilling into its center from the back side of the board. However, that requires some very precise drilling and it's difficult to verify that the TC tip is in the correct place. It's easier with a 1.27mm pitch BGA than with a tighter pitch/smaller ball, but either way it's time consuming and a pain. What we actually do is to drill the board (1/64" bit)through a pad from the top side of the board prior to placing the BGA. Then we feed a .005" TC (Omega 5SC-TT-K-36-36)through the hole from the bottom so the TC tip is even with the top of the pad and hold it in place with Loctite 3751 light setting adhesive placed at the bottom of the hole. Then we reflow the part onto the board. We use this method whether we are profiling on our Air Vac rework machine or our reflow oven for production purposes. We typically get many reflow cycles out of it and it seems to give us readings that result in good reflow profiles. --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------